The present application relates generally to design and manufacturing. It finds particular application in conjunction with three dimensional (3D) printing, and will be described with particular reference thereto. However, it is to be appreciated that the present application is also amenable to other like applications.
3D printing, also known as additive or layered manufacturing, is the process of building 3D solid shapes by accumulating material laid out in cross sectional layers. The printing process is driven by the controlled planar translation of a print head in stacked layers that determines the spatial accumulation of material. Depending on the process, the print head typically either deposits material (e.g., in fused deposition modeling (FDM)), cures powder by applying a focused laser (e.g., in selective laser sintering (SLS) and stereolithography (SLA)), sprays liquid binding onto particles (e.g., in inkjet printing), or applies some combination of these methods.
Over the last two decades, the quality and speed of 3D printers has improved, design software for 3D printers has improved, and the costs of 3D printers have fallen. Compared to conventional manufacturing, 3D printing now includes a more automated nature in the manufacturing process, and a higher range of complexity in parts that can be produced. These advantages have led to increased adoption by eclectic groups of users who are not just using 3D printed parts as prototypes, but also as final products in a wide variety of applications ranging from clothing and art to prosthetics and topologically optimized functional parts. Hence, the aesthetic qualities and visual properties of the output of a 3D printing process are increasingly important.
Unfortunately, the democratization of additive manufacturing coupled with the feasibility of producing complex geometries has led to the widespread but often erroneous belief among many users that any model that can be designed in a computer-aided design (CAD) system can be manufactured using a 3D printer. In reality, the quality of a printed model is sensitive to a combination of the chosen build orientation, material, and printer parameters. Poor understanding of how the printing parameters affect the printed model in relation to the original model often leads to failures that are only apparent after printing, even to experts. For example, a home 3D printer user will often have to print multiple attempts in order to get the desired output. As another example, service providers for 3D printed parts often have significant scrap from print failures that are a result of this poor understanding.
Printer resolution in the stacking direction dictates the deviation from the intended shape due to stair stepping artifacts in the build, and parameters such as the nozzle diameter in FDM or the beam width and/or offset in SLS influence the resolution of the smallest feature printable by the translating print head. Furthermore, the printed size of structures, such as thin walls, bridges, and spikes, affect the integrity of these structures. The printed size is also influenced by printer resolution. Hence, 3D printer manufacturers often recommend minimum material-specific sizes for these structures. The various resolutions and minimum size recommendations mentioned are unrelated to the numerical resolution chosen to triangulate solid models for representation in a stereolithography (STL) file format. This lack of coordination between the printer-related resolutions/minimum-sizes and the numerical resolutions of the STL file leads to the discrepancies between the final 3D printed object and the designed CAD model.
Users often attempt to manually predict and correct defects or deficiencies of printed parts relative to corresponding CAD models with design heuristics and rules. Predicting and correcting defects or deficiencies saves time, material, energy, and labor by not producing parts from designs with unexpected flaws that manifest themselves in the manufacturing process. However, the ability to manually predict and correct defects or deficiencies is becoming increasingly difficult as the number of printers, materials, and manufacturing services available grows.
Existing software solutions for previewing a 3D model (that is intended to be 3D printed) show the original 3D model without showing any differences that might occur due to the 3D printing process. No geometric differences are shown, and no simulation of the texture of the 3D printed object from the layered nature of the process is shown. Also, no realistic rendering of the material is shown. Typically, photos of example objects printed using specific 3D printers are available for reference, but no such photo may exist for the specific part the user intends to print.
Further, existing software to analyze and prepare models for 3D printing are often intended to accompany a specific printer (e.g. MAKERWARE for the MAKERBOT printer, OBJET STUDIO for the OBJET line of printers from STRATASYS) and typically enable some combination of model cleanup, build orientation optimization, and tool path generation. Sometimes, computational support is further provided to hollow and thicken models to minimize material wastage and reinforce thin walls.
Model cleanup refers to geometric processing of a 3D model (e.g., specified in the STL file format) to create watertight manifold shapes that do not possess duplicate vertices, self-intersections, and other types of geometric errors that can arise due to numerical problems during creation, and particularly during the process of converting the file format of the 3D model to the STL format accepted by most printers. After cleanup, models may then be analyzed to either automatically or manually select a build orientation. If chosen automatically, the software tries to find an orientation near the specified pose that minimizes the additional material required to support the model during the build. Subsequently the models are sent to a tool path generator that generates low-level G-code instructions to run the 3D printer.
In view of the foregoing, manufacturability analysis for 3D printing is typically restricted to preparing the model for printing. This analysis typically happens in prototyping shops (i.e., downstream from design engineering) or not at all. Such shops have expertise in various software tools that are bundled with 3D printers to perform optimizations or manual corrections to part geometries, such as fixing bad models, making minor design changes, etc. As mentioned earlier, these tools are machine specific, making it difficult for designers to access them. Hence, there is a need for more general design software that can predict and correct defects or deficiencies in models.
The present application provides new and improved methods and systems which improve on the above-referenced technique and address the above-referenced challenges.